Display device

ABSTRACT

A display device includes a flexible display module and provides a display area including a fingerprint recognition area, and a non-display area outside the display area. The flexible display module includes a display panel including a light-emitting element, a touch sensing unit disposed on the display panel, and a fingerprint recognition unit overlapping with the fingerprint recognition area. The touch sensing unit is configured to sense pressure applied to the flexible display module in an in-folding mode in which the flexible display module is folded such that a portion of the display area faces another portion of the display area.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of Korean PatentApplication No. 10-2016-0145405, filed Nov. 2, 2016, which is herebyincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND Field

The disclosure generally relates to a display device, and, moreparticularly, to a display device capable of sensing external appliedpressure and recognizing epidermal ridge information, such as afingerprint.

Discussion

Various types of display devices may be used in multimedia devices, suchas televisions, portable phones, tablet computers, navigation systems,game consoles, etc. Input units (or interfaces) of a display device mayinclude a keyboard, mouse, and/or the like. A display device mayadditionally or alternatively include a touch sensing unit as an inputunit. To this end, display devices may further include enhanced securityfunctions.

The above information disclosed in this section is only forunderstanding the background of the inventive concepts, and, therefore,may contain information that does not form prior art.

SUMMARY

Some exemplary embodiments are capable of providing a display deviceconfigured to sense a touch of a user and applied pressure.

Some exemplary embodiments are capable of providing a display deviceconfigured to recognize epidermal ridge information (e.g., afingerprint) of a user.

Additional aspects will be set forth in the detailed description whichfollows, and, in part, will be apparent from the disclosure, or may belearned by practice of the inventive concepts.

According to some exemplary embodiments, a display device includes aflexible display module and provides a display area including afingerprint recognition area, and a non-display area outside the displayarea. The flexible display module includes a display panel including alight-emitting element, a touch sensing unit disposed on the displaypanel, and a fingerprint recognition unit overlapping with thefingerprint recognition area. The touch sensing unit is configured tosense pressure applied to the flexible display module in an in-foldingmode in which the flexible display module is folded such that a portionof the display area faces another portion of the display area.

According to some exemplary embodiments, a display device includes aflexible display module and a force sensor. The display device providesa display area including a fingerprint recognition area, and anon-display area outside the display area. The flexible display moduleincludes a display panel including a light-emitting element, a touchsensing unit disposed on the display panel, and a fingerprintrecognition unit overlapping with the fingerprint recognition area. Thedisplay panel is disposed between the touch sensing unit and the forcesensor. The force sensor is configured to sense pressure applied to theflexible display module in an out-folding mode in which the flexibledisplay module is folded such that a portion of the display area facesan opposite direction from another portion of the display area.

According to some exemplary embodiments, a display device may include aflexible display module and may provide a display area including afingerprint recognition area, and a non-display area outside the displayarea. The flexible display module may include a display panel includinga light-emitting element, a touch sensing unit disposed on the displaypanel, and a fingerprint recognition unit overlapping with thefingerprint recognition area. The touch sensing unit is configured tosense a capacitance between a portion of the display area and anotherportion of the display area in an in-folding mode in which the flexibledisplay module is folded such that the portion of the display area facesthe another portion of the display area.

The foregoing general description and the following detailed descriptionare exemplary and explanatory and are intended to provide furtherexplanation of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the inventive concepts, and are incorporated in andconstitute a part of this specification, illustrate exemplaryembodiments of the inventive concepts, and, together with thedescription, serve to explain principles of the inventive concepts.

FIG. 1 is a perspective view illustrating a display device in a normalmode according to some exemplary embodiments.

FIGS. 2A and 2B are perspective views illustrating the display device ofFIG. 1 in in-folding modes according to various exemplary embodiments.

FIGS. 3A, 3B, 3C, and 3D are cross-sectional views illustrating displaydevices according to some exemplary embodiments.

FIG. 4 is a plan view illustrating a display panel according to someexemplary embodiments.

FIG. 5 is an equivalent circuit diagram of a pixel according to someexemplary embodiments.

FIGS. 6 and 7 are partial cross-sectional views illustrating a displaypanel according to some exemplary embodiments.

FIG. 8 is a plan view illustrating a touch sensing unit according tosome exemplary embodiments.

FIG. 9 is an enlarged view of portion AA of FIG. 8 according to someexemplary embodiments.

FIGS. 10A and 10B are cross-sectional views taken along sectional lineII-II′ of FIG. 9 according to some exemplary embodiments.

FIG. 11A is a plan view illustrating touch sensors disposed in a touchsensing area according to some exemplary embodiments.

FIG. 11B is a cross-sectional view taken along sectional line I-I′ ofFIG. 2A according to some exemplary embodiments.

FIG. 12A is a plan view illustrating touch sensors disposed in a touchsensing area according to some exemplary embodiments.

FIG. 12B is a cross-sectional view taken along the line I-I′ of FIG. 2Aaccording to some exemplary embodiments.

FIG. 13 is a block diagram illustrating a display device according tosome exemplary embodiments.

FIG. 14A is a perspective view illustrating a display device in a normalmode according to some exemplary embodiments.

FIGS. 14B and 14C are perspective views illustrating the display deviceof FIG. 14A in out-folding modes according to various exemplaryembodiments.

FIG. 15A is a cross-sectional view taken along sectional line III-III′of FIG. 14A according to some exemplary embodiments.

FIG. 15B is a cross-sectional view taken along sectional line IV-IV′ ofFIG. 14B according to some exemplary embodiments.

FIG. 16A is a cross-sectional view taken along sectional line III-III′of FIG. 14A according to some exemplary embodiments.

FIG. 16B is a cross-sectional view taken along sectional line IV-IV′ ofFIG. 14B according to some exemplary embodiments.

FIG. 16C illustrates strain gauges of the display device of FIG. 16Aaccording to some exemplary embodiments.

FIG. 17 is a perspective view illustrating a display device according tosome exemplary embodiments.

FIG. 18 is a partial cross-sectional view illustrating a display deviceaccording to some exemplary embodiments.

FIG. 19 is a partial cross-sectional view illustrating a display deviceaccording to some exemplary embodiments.

FIG. 20 is a partial cross-sectional view illustrating a display deviceaccording to some exemplary embodiments.

FIG. 21 is a cross-sectional view illustrating a display deviceaccording to some exemplary embodiments.

FIGS. 22, 23, 24, 25, and 26 are cross-sectional views illustratingforce sensors according to various exemplary embodiments.

FIGS. 27, 28, and 29 illustrate touch sensing units according to variousexemplary embodiments.

FIG. 30A is a perspective view illustrating a display device in a normalmode according to some exemplary embodiments.

FIG. 30B is a perspective view illustrating the display device of FIG.30A in an in-folding mode according to some exemplary embodiments.

FIG. 31A is a perspective view illustrating a display device in a normalmode according to some exemplary embodiments.

FIGS. 31B and 31C are perspective views illustrating the display deviceof FIG. 31A in folding modes according to various exemplary embodiments.

FIG. 32A is a cross-sectional view taken along sectional line V-V′ ofFIG. 31B according to some exemplary embodiments.

FIG. 32B is a cross-sectional view taken along sectional line VI-VI′ ofFIG. 31C according to some exemplary embodiments.

FIG. 33 is a perspective view illustrating a display device according tosome exemplary embodiments.

FIGS. 34A and 34B are plan views illustrating touch sensing unitsaccording to various exemplary embodiments.

FIG. 35 is a cross-sectional view illustrating a display device in anin-folding state according to some exemplary embodiments.

FIG. 36 is a cross-sectional view illustrating a display device in anout-folding state according to some exemplary embodiments.

FIG. 37 is a cross-sectional view illustrating a display device in anout-folding state according to some exemplary embodiments.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various exemplary embodiments. It is apparent, however,that various exemplary embodiments may be practiced without thesespecific details or with one or more equivalent arrangements. In otherinstances, well-known structures and devices are shown in block diagramform in order to avoid unnecessarily obscuring various exemplaryembodiments. Further, various exemplary embodiments may be different,but do not have to be exclusive. For example, specific shapes,configurations, and characteristics of an exemplary embodiment may beimplemented in another exemplary embodiment without departing from thespirit and the scope of the disclosure.

Unless otherwise specified, the illustrated exemplary embodiments are tobe understood as providing exemplary features of varying detail of someexemplary embodiments. Therefore, unless otherwise specified, thefeatures, components, modules, layers, films, panels, regions, aspects,etc. (hereinafter individually or collectively referred to as“elements”), of the various illustrations may be otherwise combined,separated, interchanged, and/or rearranged without departing from thespirit and the scope of the disclosure.

The use of cross-hatching and/or shading in the accompanying drawings isgenerally provided to clarify boundaries between adjacent elements. Assuch, neither the presence nor the absence of cross-hatching or shadingconveys or indicates any preference or requirement for particularmaterials, material properties, dimensions, proportions, commonalitiesbetween illustrated elements, and/or any other characteristic,attribute, property, etc., of the elements, unless specified. Further,in the accompanying drawings, the size and relative sizes of elementsmay be exaggerated for clarity and/or descriptive purposes. Thus, theaccompanying drawings are schematic in nature, and, therefore, exemplaryembodiments are not be construed as limited to the illustrated shapes,but are to include deviations that result, for example, frommanufacturing. When an exemplary embodiment may be implementeddifferently, a specific process order may be performed differently fromthe described order. For example, two consecutively described processesmay be performed substantially at the same time or performed in an orderopposite to the described order. Also, like reference numerals denotelike elements.

When an element is referred to as being “on,” “connected to,” or“coupled to” another element, it may be directly on, connected to, orcoupled to the other element or intervening elements may be present.When, however, an element is referred to as being “directly on,”“directly connected to,” or “directly coupled to” another element, thereare no intervening elements present. To this end, the term “connected”may refer to physical, electrical, and/or fluid connection. Further, theD1-axis, the D2-axis, and the D3-axis are not limited to three axes of arectangular coordinate system, and may be interpreted in a broadersense. For example, the D1-axis, the D2-axis, and the D3-axis may beperpendicular to one another, or may represent different directions thatare not perpendicular to one another. For the purposes of thisdisclosure, “at least one of X, Y, and Z” and “at least one selectedfrom the group consisting of X, Y, and Z” may be construed as X only, Yonly, Z only, or any combination of two or more of X, Y, and Z, such as,for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items.

Although the terms “first,” “second,” etc. may be used herein todescribe various elements, these elements should not be limited by theseterms. These terms are used to distinguish one element from anotherelement. Thus, a first element discussed below could be termed a secondelement without departing from the teachings of the disclosure.

Spatially relative terms, such as “beneath,” “below,” “under,” “lower,”“above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), andthe like, may be used herein for descriptive purposes, and, thereby, todescribe one element's relationship to another element(s) as illustratedin the drawings. Spatially relative terms are intended to encompassdifferent orientations of an apparatus in use, operation, and/ormanufacture in addition to the orientation depicted in the drawings. Forexample, if the apparatus in the drawings is turned over, elementsdescribed as “below” or “beneath” other elements or features would thenbe oriented “above” the other elements or features. Thus, the exemplaryterm “below” can encompass both an orientation of above and below.Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90degrees or at other orientations), and, as such, the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting. As used herein, thesingular forms, “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Moreover,the terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components, and/orgroups thereof, but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof. It is also noted that, as used herein, the terms“approximately,” “substantially,” “about,” and other similar terms, areinclusive of a stated value, but used as terms of approximation and notas terms of degree, and, as such, are utilized to account for inherentdeviations in measured, calculated, and/or provided values that would berecognized by one of ordinary skill in the art.

Various exemplary embodiments are described herein with reference tosectional and/or exploded illustrations that are schematic illustrationsof idealized exemplary embodiments and/or intermediate structures. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, exemplary embodiments disclosed herein should not beconstrued as limited to the particular illustrated shapes of regions,but are to include deviations in shapes that result from, for instance,manufacturing. In this manner, regions illustrated in the drawings areschematic in nature and shapes of these regions may not illustrate theactual shapes of regions of a device, and, as such, are not intended tobe limiting.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure is a part. Terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and will not be interpreted in anidealized or overly formal sense, unless expressly so defined herein

FIG. 1 is a perspective view illustrating a display device DD in anormal mode according to some exemplary embodiments. FIGS. 2A and 2B areperspective views illustrating the display device DD in in-folding modesaccording to various exemplary embodiments.

As illustrated in FIG. 1, in a normal mode, a display surface IS onwhich an image IM is displayed is parallel to a plane defined by a firstdirectional axis DR1 and a second directional axis DR2. A normaldirection of the display surface IS (e.g., a thickness direction of thedisplay device DD) is parallel to a third directional axis DR3. A frontsurface (or a top surface) and a back surface (or a bottom surface) ofeach of the members are defined by the third directional axis DR3.However, directions indicated by the first to third directional axesDR1, DR2, and DR3 may be relative concepts and may be changed into otherdirections. Hereinafter, first to third directions are the directionsindicated by the first to third directional axes DR1, DR2, and DR3,respectively, and are indicated by the same reference designators as thefirst to third directional axes DR1, DR2, and DR3. For convenience, aflexible display device is described and illustrated; however, exemplaryembodiments are not limited thereto. For instance, the display device DDmay be a rigid display device.

FIGS. 1 and 2A illustrate a foldable display device as an example of thedisplay device DD. However, the display device DD may be, but is notlimited to, a rollable display device. The display device DD may be usedin large-sized electronic devices (e.g., televisions, monitors, etc.)and small and medium-sized electronic devices (e.g., portable phones,tablets, car navigation units, game consoles, smart watches, etc.).

As illustrated in FIG. 1, the display surface IS of the display deviceDD may include a plurality of areas. The display surface IS includes adisplay (or active) area DD-DA in which the image IM is displayed, and anon-display (inactive) area DD-NDA adjacent to (e.g., outside) thedisplay area DD-DA. An image is not displayed in the non-display areaDD-NDA. In FIG. 1, application icons are illustrated as an example ofthe image IM, but exemplary embodiments are not limited thereto orthereby. The display area DD-DA may have a quadrilateral shape. Thenon-display area DD-NDA may surround the display area DD-DA. However,exemplary embodiments are not limited thereto or thereby. The shapes ofthe display area DD-DA and the non-display area DD-NDA may be relativelydesigned.

The display area DD-DA may include a fingerprint recognition area FPA.The fingerprint recognition area FPA may recognize a fingerprint of auser; however, it is contemplated that the fingerprint sensing area FPAmay be utilized to sense other epidermal ridge information, such as apalm print, a footprint, etc., or may be utilized to sense other formsof three-dimensional patterns, such as a three-dimensional barcode, etc.For convenience, fingerprint detection will be described andillustrated.

When a user, for example, touches the fingerprint recognition area FPA,the display device DD may recognize a fingerprint of the user todetermine whether the user is a valid user or not. The fingerprint ofthe user may be used for portable device security, financialtransactions, and control of a system. According to some exemplaryembodiments, the fingerprint recognition area FPA is included in thedisplay area DD-DA. However, exemplary embodiments are not limitedthereto or thereby. In other exemplary embodiments, the fingerprintrecognition area FPA may be included in the non-display area DD-NDA. Instill other exemplary embodiments, the fingerprint recognition area FPAmay be included in both the display area DD-DA and the non-display areaDD-NDA.

Although not shown in the drawings, the display device DD may include ahousing. The housing may be disposed at an outer periphery of thedisplay device DD and may receive and/or support various parts therein.

As illustrated in FIGS. 1, 2A, and 2B, the display device DD may includea plurality of areas defined according to an operation mode. The displaydevice DD may include a bending area BA bent on the basis of a bendingaxis BX, a first non-bending area NBA1, and a second non-bending areaNBA2. The first and second non-bending areas NBA1 and NBA2 are not bent.

As illustrated in FIG. 2A, the display device DD may be inner-bent suchthat the display surface IS of the first non-bending area NBA1 faces thedisplay surface IS of the second non-bending area NBA2. In someexemplary embodiments, the bending case in which the display surface ISof the first non-bending area NBA1 faces the display surface IS of thesecond non-bending area NBA2 is defined as an in-folding mode. A casewhich is not the in-folding mode may be defined as a normal mode, suchas illustrated in FIG. 1.

In some exemplary embodiments, the display device DD may include aplurality of bending areas BA. In addition, the bending area BA may bedefined or designed to correspond to a manner in which a user operatesthe display device DD. For example, unlike FIG. 2A, the bending area BAmay be defined or designed to be parallel to the first directional axisDR1 or may be defined or designed in a diagonal direction. An area ofthe bending area BA may not be fixed, but may be determined depending onto a radius of curvature. In some exemplary embodiments, the displaydevice DD may be repeatedly operated between the operation modesillustrated in FIGS. 1, 2A, and 2B.

As previously described, FIG. 1 is a perspective view illustrating adisplay device DD in a normal mode, whereas FIGS. 2A and 2B areperspective views illustrating the display device DD of FIG. 1 inin-folding modes according to some exemplary embodiments. To this end,FIG. 2B illustrates an example of the display device DD in which afolding portion is different from that of the display device DD of FIG.2A. As such, exemplary embodiments are not limited to the number of thebending area BA and the non-bending area NBA of the display device DD,nor are exemplary embodiments limited to a position of the bending areaBA of the display device DD.

Referring to FIG. 2B, the fingerprint recognition area FPA is exposed tothe outside in an in-folding mode. The fingerprint recognition area FPAexposed to the outside may recognize a fingerprint of a user. In someexemplary embodiments, a user can set security and/or control the devicethrough fingerprint recognition even though the display device DD is inthe in-folding mode, and, thus, convenience and security of a user canbe improved.

FIGS. 3A, 3B, 3C, and 3D are cross-sectional views illustrating displaydevices according to some exemplary embodiments. It is noted that FIGS.3A to 3D illustrate cross-sections defined by the second directionalaxis DR2 and the third directional axis DR3.

As illustrated in FIGS. 3A to 3D, the display device DD or DD-E includesa protective film PM, a window WM, a display module DM or DM-E, a firstadhesive member AM1, and a second adhesive member AM2. The displaymodule DM or DM-E is disposed between the protective film PM and thewindow WM. The first adhesive member AM1 couples the display module DMor DM-E and the protective film PM to each other, and the secondadhesive member AM2 couples the display module DM or DM-E and the windowWM to each other. In some exemplary embodiments, the first adhesivemember AM1 and the second adhesive member AM2 may be omitted. Each ofthe protective film PM and the window WM may be continuously formedthrough a coating process.

The protective film PM protects the display module DM or DM-E. Theprotective film PM provides or includes a first outer surface OS-Lexposed to the outside and an adhesive surface adhered to the firstadhesive member AM1. The protective film PM prevents (or reduces)external moisture from permeating into the display module DM and absorbsan external impact.

The protective film PM may include a plastic film as a base layer. Theprotective film PM may include the plastic film that includes oneselected from a group consisting of polyethersulfone (PES),polyacrylate, polyetherimide (PEI), polyethylenenaphthalate (PEN),polyethyleneterephthalate (PET), polyphenylene sulfide (PPS),polyarylate, polyimide (PI), polycarbonate (PC), poly(aryleneethersulfone), and any combination thereof. The material of theprotective film PM is not limited to plastic resins, but may include anorganic/inorganic composite material. For example, the protective filmPM may include a porous organic layer and an inorganic material fillingpores of the porous organic layer. The protective film PM may furtherinclude a functional layer formed on the plastic film. The functionallayer may include a resin layer. The functional layer may be formed by acoating method.

The window WM may protect the display module DM or DM-E from an externalimpact and may provide an input surface to a user. The window WMprovides or includes a second outer surface OS-U exposed to the outsideand an adhesive surface adhered to the second adhesive member AM2. Thedisplay surface IS illustrated in FIGS. 1, 2A, and 2B may be the secondouter surface OS-U. The second outer surface OS-U may also be a touchsensing surface for sensing a touch of a user.

As illustrated in FIGS. 1, 2A, and 2B, the window WM of the displaydevice DD may not be disposed in the bending area BA; however, exemplaryembodiments are not limited thereto or thereby. In some exemplaryembodiments, the window WM may also be disposed in the bending area BA.

Adverting to FIGS. 3A to 3D, in some exemplary embodiments, the displaymodule DM or DM-E may include a display panel DP, a touch sensing unit(or structure) TS, and a fingerprint recognition unit (or structure) FPSor FPS-E. The display panel DP may include a light-emitting element. Thedisplay panel DP generates the image IM (see FIG. 1) corresponding toinput image data. The display panel DP provides or includes a firstdisplay panel surface BS1-L and a second display panel surface BS1-Uthat are opposite to each other in the thickness direction DR3. Aprocess of forming the display panel DP may include a low-temperaturepolycrystalline silicon (LTPS) process or a low-temperaturepolycrystalline oxide (LTPO) process.

The touch sensing unit TS obtains information on coordinates of externalinput. The touch sensing unit TS may also be referred to as an inputsensing unit. The external input may include a touch by a human fingerFG, a touch by a touch pen, a hovering action, an approach, and/or thelike. The touch sensing unit TS may be disposed directly on the seconddisplay panel surface BS1-U. That is, the touch sensing unit TS may beintegrally manufactured with the display panel DP by continuousprocesses; however, exemplary embodiments are not limited thereto orthereby. In some exemplary embodiments, the touch sensing unit TS may bemanufactured by a separate process and may be adhered to the displaypanel DP.

Although not shown in the drawings, the display module DM or DM-Eaccording to some exemplary embodiments may further include ananti-reflection layer. The anti-reflection layer may include a colorfilter, a stack structure of a conductive layer/a dielectric layer/aconductive layer, or an optical member. The anti-reflection layer mayabsorb, destructively interfere with, or polarize external lightincident from the outside to reduce a reflectance of the external light.

Each of the first and second adhesive members AM1 and AM2 may be atleast one of optically clear adhesive (OCA) film, an optically clearresin (OCR), and a pressure sensitive adhesive (PSA) film. Each of thefirst and second adhesive members AM1 and AM2 may include, but is notlimited to, a photo-curing adhesive material or a thermosetting adhesivematerial.

Although not shown in the drawings, the display device DD or DD-E mayfurther include a frame structure that supports functional layers tomaintain the states of the display device DD illustrated in FIGS. 1, 2A,and 2B. The frame structure may include a joint structure or a hingestructure; however, any other suitable structure may be utilized.

In some exemplary embodiments, the touch sensing unit TS may besingle-layered. In other words, the touch sensing unit TS may include asingle conductive layer. Here, the single conductive layer means that aconductive layer separated by an insulating layer is one. A stackstructure of a first metal layer/a second metal layer/a metal oxidelayer corresponds to the single conductive layer, and a stack structureof a metal layer/an insulating layer/a metal oxide layer corresponds toa double conductive layer.

According to various exemplary embodiments, the single conductive layeris patterned to form a plurality of touch sensors and a plurality oftouch signal lines, as will become more apparent below, but are notillustrated in FIGS. 3A to 3D. In other words, the touch sensors of thetouch sensing unit TS may be disposed on the same layer. The touchsensors may be disposed directly on a thin film sealing layer TFE (referto FIG. 6). In addition, a portion of each of the touch signal lines maybe disposed on the same layer as the touch sensors.

In some exemplary embodiments, the touch signal lines and the touchsensors may include indium-tin oxide (ITO), indium-zinc oxide (IZO),zinc oxide (ZnO), indium-tin-zinc oxide (ITZO), PEDOT, a metal nanowire,and/or graphene. In some exemplary embodiments, the touch signal linesand the touch sensors may include a metal layer, e.g., molybdenum,silver, titanium, copper, aluminum, or any alloy thereof. The touchsignal lines and the touch sensors may include the same material ormaterials different from each other. However, exemplary embodiments arenot limited thereto or thereby. In some exemplary embodiments, the touchsensing unit TS may have a multi-layered structure including a pluralityof conductive layers.

Referring to FIGS. 3A and 3B, the fingerprint recognition unit FPS isdisposed to overlap with the fingerprint recognition area FPA in thethird direction DR3. The fingerprint recognition unit FPS may bedisposed under the display panel DP. In some exemplary embodiments, thefingerprint recognition unit FPS may include a sensing module TRM andRCV. The sensing module TRM and RCV may include at least one of anoptical sensing module or an ultrasonic sensing module. The sensingmodule TRM and RCV may include a signal generator TRM and a signalreceiver RCV.

The signal generator TRM generates a first signal SGN1 directed to afingerprint of a finger FG of a user. In some exemplary embodiments, inthe case in which the sensing module TRM and RCV is the optical sensingmodule, the first signal SGN1 may be an optical signal. In someexemplary embodiments, in the case in which the sensing module TRM andRCV is the ultrasonic sensing module, the first signal SGN1 may be anultrasonic signal.

The signal receiver RCV receives a second signal SGN2. The second signalSGN2 is generated by reflection of the first signal SGN1 from thefingerprint of the finger FG of the user. When the first signal SGN1 isthe optical signal, the second signal SGN2 may also be an opticalsignal. When the first signal SGN1 is the ultrasonic signal, the secondsignal SGN2 may also be an ultrasonic signal.

In some exemplary embodiments, the sensing module TRM and RCV mayanalyze the first signal SGN1 generated from the signal generator TRMand the second signal SGN2 received by the signal receiver RCV, therebyrecognizing the fingerprint of the finger FG of the user. In otherwords, the sensing module TRM and RCV may recognize the fingerprint byusing a difference between light (or sound) reflected from a ridge ofthe fingerprint and light (or sound) reflected from a valley of thefingerprint.

Referring to FIGS. 3C and 3D, a fingerprint recognition unit FPS-E ofthe display module DM-E of the display device DD-E is disposed tooverlap with the fingerprint recognition area FPA in the third directionDR3. The fingerprint recognition unit FPS-E may be disposed on the touchsensing unit TS.

The fingerprint recognition unit FPS-E may include a plurality offingerprint sensing electrodes ET-F. The fingerprint sensing electrodesET-F may be capacitively coupled to a finger FG of a user. Capacitancesgenerated between the fingerprint of the finger FG of the user and thefingerprint sensing electrodes ET-F may be different from each otheraccording to a pattern of the fingerprint, e.g., a pattern of thevalleys and ridges of the fingerprint. As such, the fingerprintrecognition unit FPS-E may sense these differences between thecapacitances to recognize the fingerprint. In other words, thefingerprint recognition unit FPS-E may recognize the fingerprint byusing a difference between a capacitance occurring in association with aridge of the fingerprint and a capacitance occurring in association witha valley of the fingerprint.

The fingerprint recognition unit FPS or FPS-E can recognize thefingerprint not only when the finger FG of the user is in contact withthe unit FPS or FPS-E, but also when the finger FG moves in the state inwhich the finger FG is in contact with the unit FPS or FPS-E. However,the fingerprint recognition units FPS and FPS-E are not limited to or bythe aforementioned exemplary embodiments. In some exemplary embodiments,at least one of other various kinds of sensors may be used as thefingerprint recognition unit FPS or FPS-E. For example, the fingerprintrecognition unit may be a heat sensing type or a non-contact type.

FIG. 4 is a plan view illustrating a display panel DP according to someexemplary embodiments. FIG. 5 is an equivalent circuit diagram of apixel PX according to some exemplary embodiments. FIGS. 6 and 7 arepartial cross-sectional views illustrating a display panel DP accordingto some exemplary embodiments.

As illustrated in FIG. 4, the display panel DP includes a display areaDA and a non-display area NDA when viewed in a plan view. The displayarea DA and the non-display area NDA of the display panel DP correspondto the display area DD-DA and the non-display area DD-NDA of the displaydevice DD, respectively. However, the display area DA and thenon-display area NDA of the display panel DP need not be the same as thedisplay area DD-DA and the non-display area DD-NDA of the display deviceDD, but may be changed according to a structure and/or a design of thedisplay panel DP.

The display panel DP includes a plurality of signal lines SGL and aplurality of pixels PX. An area in which the plurality of pixels PX isdisposed is defined as the display area DA. In some exemplaryembodiments, the non-display area NDA may be defined along a border ofthe display area DA.

The plurality of signal lines SGL may include gate lines GL, data linesDL, a power line PL, and a control signal line CSL. Each of the gatelines GL is connected to corresponding ones of the plurality of pixelsPX, and each of the data lines DL is connected to corresponding ones ofthe plurality of pixels PX. The power line PL is connected to theplurality of pixels PX. A gate driving circuit DCV to which the gatelines GL are connected may be disposed at one side portion of thenon-display area NDA; however, exemplary embodiments are not limitedthereto or thereby. The control signal line CSL may provide controlsignals to the gate driving circuit DCV.

One or some of the gate lines GL, the data lines DL, the power line PL,and the control signal line CSL may be disposed in one layer, andanother or others of the gate lines GL, the data lines DL, the powerline PL, and the control signal line CSL may be disposed in anotherlayer different from the one layer. The signal lines SGL disposed in theone layer of the gate lines GL, the data lines DL, the power line PL,and the control signal line CSL may be defined as first signal lines,and the signal lines SGL disposed in the another layer may be defined assecond signal lines. The signal lines disposed in still another layermay be defined as third signal lines.

Each of the gate lines GL, the data lines DL, the power line PL, and thecontrol signal line CSL may include a signal interconnection portion anda display panel pad PD-DP connected to an end of the signalinterconnection portion. The signal interconnection portion may bedefined as a portion of each of the signal lines SGL except the displaypanel pads PD-DP.

The display panel pads PD-DP may be formed in a same process astransistors (see, e.g., first transistor TFT1 of FIG. 6) for driving thepixels PX. For example, the display panel pads PD-DP may be formed inthe same low-temperature polycrystalline silicon (LTPS) process orlow-temperature polycrystalline oxide (LTPO) process as the transistorsfor driving the pixels PX.

In some exemplary embodiments, the display panel pads PD-DP may includea control pad CSL-P, a data pad DL-P, and a power pad PL-P. A gate padis not illustrated; however, the gate pad may overlap with the gatedriving circuit DCV and/or may be connected to the gate driving circuitDCV. Even though not indicated in the drawings, a portion of thenon-display area NDA in which the control pad CSL-P, the data pad DL-P,and the power pad PL-P are arranged, may be defined as a pad area. Asdescribed later, pads of the touch sensing unit TS may be disposedadjacent to the aforementioned pads of the display panel PD.

The pixel PX connected to one gate line GL, one data line DL, and thepower line PL is illustrated as a representative example in FIG. 5. Itis noted, however, that the configuration of the pixel PX is not limitedto the configuration illustrated and described in association with FIG.5, but may be variously modified.

The pixel PX includes a light-emitting element OLED used as a displayelement. The light-emitting element OLED may be a front surfacelight-emitting type diode or a back surface light-emitting type diode.Alternatively, the light-emitting element OLED may be a both surfacelight-emitting type diode. The pixel PX includes a first transistor (ora switching transistor) TFT1, a second transistor (or a drivingtransistor) TFT2, and a capacitor CAP that constitute a circuit part fordriving the light-emitting element OLED. The light-emitting element OLEDgenerates light based on an electrical signal provided from the firstand second transistors TFT1 and TFT2.

The first transistor TFT1 outputs a data signal applied to the data lineDL (or corresponding to another data signal applied to the data line DL)in response to a scan signal applied to the gate line GL. The capacitorCAP is charged with a voltage corresponding to the data signal receivedfrom the first transistor TFT1.

The second transistor TFT2 is connected to the light-emitting elementOLED. The second transistor TFT2 controls a driving current flowingthrough the light-emitting element OLED in response to the amount ofcharge stored in the capacitor CAP. The light-emitting element OLEDemits light while the second transistor TFT2 is turned-on.

FIG. 6 is a cross-sectional view of a portion of the display panel DPincluding or corresponding to the first transistor TFT1 and thecapacitor CAP of the equivalent circuit illustrated in FIG. 5. FIG. 7 isa cross-sectional view of a portion of the display panel DP including orcorresponding to the second transistor TFT2 and the light-emittingelement OLED of the equivalent circuit illustrated in FIG. 5.

As illustrated in FIGS. 6 and 7, a first circuit layer CL1 is disposedon a base layer SUB. A semiconductor pattern AL1 (hereinafter, referredto as a “first semiconductor pattern”) of the first transistor TFT1 anda semiconductor pattern AL2 (hereinafter, referred to as a “secondsemiconductor pattern”) of the second transistor TFT2 are disposed onthe base layer SUB. Each of the first and second semiconductor patternsAL1 and AL2 may include at least one of amorphous silicon, poly-silicon,or a metal oxide semiconductor. Here, the first and second semiconductorpatterns AL1 and AL2 may include the same material or differentmaterials from each other.

The first circuit layer CL1 may include organic/inorganic layers BR, BF,12, 14, and 16, the first transistor TFT1, the second transistor TFT2,and electrodes E1 and E2. The organic/inorganic layers BR, BF, 12, 14,and 16 may include a functional layer BR and BF, a first insulatinglayer 12, a second insulating layer 14, and a third insulating layer 16.

The functional layer BR and BF may be disposed on one surface of thebase layer SUB. The functional layer BR and BF includes at least one ofa barrier layer BR and a buffer layer BF. The first semiconductorpattern AL1 and the second semiconductor pattern AL2 may be disposed onthe barrier layer BR or the buffer layer BF.

The first insulating layer 12 is disposed on the base layer SUB andcovers the first semiconductor pattern AL1 and the second semiconductorpattern AL2. The first insulating layer 12 includes an organic layerand/or an inorganic layer. The first insulating layer 12 may include aplurality of inorganic thin layers. The plurality of inorganic thinlayers may include a silicon nitride layer and a silicon oxide layer.

A control electrode GE1 (hereinafter, referred to as a “first controlelectrode”) of the first transistor TFT1 and a control electrode GE2(hereinafter, referred to as a “second control electrode”) of the secondtransistor TFT2 are disposed on the first insulating layer 12. A firstelectrode E1 of the capacitor CAP is disposed on the first insulatinglayer 12. The first control electrode GE1, the second control electrodeGE2, the first electrode E1, and the gate lines GL (see FIG. 5) may beformed using the same photolithography process. In other words, thefirst control electrode GE1, the second control electrode GE2, the firstelectrode E1, and the gate lines GL may be formed of the same materialand the same stack structure, and may be disposed on the same layer,e.g., the first insulating layer 12.

The second insulating layer 14 is disposed on the first insulating layer12 and covers the first control electrode GE1, the second controlelectrode GE2, and the first electrode E1. The second insulating layer14 includes an organic layer and/or an inorganic layer. For instance,the second insulating layer 14 may include a plurality of inorganic thinlayers. The plurality of inorganic thin layers may include a siliconnitride layer and a silicon oxide layer.

The data lines DL (see FIG. 5) may be disposed on the second insulatinglayer 14. An input electrode SE1 (hereinafter, referred to as a “firstinput electrode”) and an output electrode DE1 (hereinafter, referred toas a “first output electrode”) of the first transistor TFT1 are disposedon the second insulating layer 14. An input electrode SE2 (hereinafter,referred to as a “second input electrode”) and an output electrode DE2(hereinafter, referred to as a “second output electrode”) of the secondtransistor TFT2 are disposed on the second insulating layer 14. Thefirst input electrode SE1 is branched from a corresponding one of thedata lines DL. The power line PL (see FIG. 5) and the data lines DL maybe disposed on the same layer. The second input electrode SE2 may bebranched from the power line PL.

A second electrode E2 of the capacitor CAP is disposed on the secondinsulating layer 14. The second electrode E2, the data lines DL and thepower line PL may be formed using the same photolithography process, mayhave the same material and the same stack structure, and may be disposedon the same layer.

The first input electrode SE1 and the first output electrode DE1 areconnected to portions of the first semiconductor pattern AL1 through afirst through-hole CH1 and a second through-hole CH2 penetrating thefirst and second insulating layers 12 and 14, respectively. The firstoutput electrode DE1 may be electrically connected to the firstelectrode E1. For example, the first output electrode DE1 may beconnected to the first electrode E1 through a through-hole (not shown)penetrating the second insulating layer 14. The second input electrodeSE2 and the second output electrode DE2 are connected to portions of thesecond semiconductor pattern AL2 through a third through-hole CH3 and afourth through-hole CH4 penetrating the first and second insulatinglayers 12 and 14, respectively. Although described and illustrated astop gate structures, in some exemplary embodiments, the first transistorTFT1 and/or the second transistor TFT2 may have bottom gate structures,dual gate structures, etc.

The third insulating layer 16 is disposed on the second insulating layer14 and covers the first input electrode SE1, the first output electrodeDE1, the second input electrode SE2, and the second output electrodeDE2, and the second electrode E2. The third insulating layer 16 includesan organic layer and/or an inorganic layer. For instance, the thirdinsulating layer 16 may include an organic material to provide a flatsurface.

One of the first, second, and third insulating layers 12, 14, and 16 maybe omitted according to a circuit structure of the pixel PX. Each of thesecond and third insulating layers 14 and 16 may be defined as aninterlayer insulating layer. The interlayer insulating layer is disposedbetween a conductive pattern disposed thereunder and a conductivepattern disposed thereon to insulate the conductive patterns from eachother.

A light-emitting element layer ELL is disposed on the third insulatinglayer 16. The light-emitting element layer ELL includes a pixel-defininglayer PXL and the light-emitting element OLED. An anode AE is disposedon the third insulating layer 16. The anode AE is connected to thesecond output electrode DE2 through a fifth through-hole CH5 penetratingthe third insulating layer 16. An opening OP is defined in thepixel-defining layer PXL. The opening OP of the pixel-defining layer PXLexposes at least a portion of the anode AE.

The light-emitting element layer ELL includes a light emitting area PXAand a non-light emitting area NPXA adjacent to the light emitting areaPXA. The non-light emitting area NPXA may surround the light emittingarea PXA. In some exemplary embodiments, the light emitting area PXA isdefined to correspond to the anode AE. However, the light emitting areaPXA is not limited thereto or thereby. In other words, it is sufficientthat the light emitting area PXA is defined as an area from which lightis generated. In some exemplary embodiments, the light emitting area PXAmay be defined to correspond to a portion of the anode AE that isexposed by the opening OP.

A hole control layer HCL may be disposed in common in both the lightemitting area PXA and the non-light emitting area NPXA. Even though notshown in the drawings, a common layer, such as the hole control layerHCL, may be formed in common in the plurality of pixels PX (see FIG. 4).

A light-emitting layer EML is disposed on the hole control layer HCL.The light-emitting layer EML may be disposed in only an areacorresponding to the opening OP. In other words, the light-emittinglayers EML of the pixels PX may be separated from each other. Thelight-emitting layer EML may include an organic material or an inorganicmaterial.

An electron control layer ECL is disposed on the light-emitting layerEML. A cathode CE is disposed on the electron control layer ECL. Thecathode CE is disposed in common in the plurality of pixels PX.

In some exemplary embodiments, the patterned light-emitting layer EML isillustrated as an example. In some exemplary embodiments, thelight-emitting layer EML may be disposed in common in the plurality ofpixels PX. In this manner, the light-emitting layer EML may generatewhite light. In some exemplary embodiments, the light-emitting layer EMLmay have a multi-layered structure.

According to some exemplary embodiments, a thin film sealing layer TFEdirectly covers the cathode CE. In some exemplary embodiments, a cappinglayer (not shown) covering the cathode CE may further be disposed. Inthis case, the thin film sealing layer TFE may directly cover thecapping layer. The thin film sealing layer TFE may include an organiclayer including an organic material and an inorganic layer including aninorganic material.

In some exemplary embodiments, the non-light emitting area NPXA mayinclude a transmission area TMA. An opening OPN overlapping with thetransmission area TMA may be defined in the display panel DP. In thetransmission area TMA, the light or ultrasonic wave generated from thefingerprint recognition unit FPS may pass through the opening OPN. When,however, the display module DM-E includes the capacitance-typefingerprint recognition unit FPS-E illustrated in FIGS. 3C and 3D, thenon-light emitting area NPXA may not include the transmission area TMA.

FIG. 8 is a plan view illustrating a touch sensing unit TS according tosome exemplary embodiments.

The touch sensing unit TS includes a touch sensing area (or active area)TA and a touch non-sensing area (or inactive area) NTA when viewed in aplan view. The touch sensors for sensing a touch may be disposed in thetouch sensing area TA. Touch signal lines for electrically connectingthe touch sensors to touch sensing unit pads PD-TS may be disposed inthe touch non-sensing area NTA.

The touch sensing unit pads PD-TS are electrically connected to padsPD-PCB of a printed circuit board PCB. An integrated circuit DIC may bedisposed on the printed circuit board PCB. The integrated circuit DICmay be formed by a chip-on-flexible printed circuit (COF) method. Theintegrated circuit DIC may control the touch sensing unit TS. In someexemplary embodiments, the integrated circuit DIC may control thedisplay panel DP as well as the touch sensing unit TS.

FIG. 9 is an enlarged view of portion AA of FIG. 8 according to someexemplary embodiments. FIGS. 10A and 10B are cross-sectional views takenalong sectional line II-II′ of FIG. 9 according to some exemplaryembodiments.

Referring to FIG. 9, the touch sensing area TA includes a plurality ofthe light emitting areas PXA and the non-light emitting area NPXAsurrounding the light emitting areas PXA. A first touch sensor SP1overlaps with the non-light emitting area NPXA. The first touch sensorSP1 includes a plurality of first extensions SP1-A extending in a fifthdirection DR5 and a plurality of second extensions SP1-B extending in asixth direction DR6 intersecting the fifth direction DR5. Each of theplurality of first extension SP1-A and each of the plurality of secondextension SP1-B may be defined as a mesh line. A width of the mesh linemay be several micrometers.

The plurality of first extensions SP1-A and the plurality of secondextensions SP1-B are connected to each other to define a plurality oftouch openings TS-OP. In other words, the first touch sensor SP1 has amesh shape including the plurality of touch openings TS-OP. In someexemplary embodiments, the touch openings TS-OP correspond to the lightemitting areas PXA, respectively. However, exemplary embodiments are notlimited thereto or thereby. In some exemplary embodiments, one touchopening TS-OP may correspond to two or more light emitting areas PXA.

Sizes (e.g., areas) of the light emitting areas PXA may be various. Forexample, the sizes of the light emitting areas PXA providing blue lightmay be different from those of the light emitting areas PXA providingred light. Thus, sizes (e.g., areas) of the touch openings TS-OP mayalso be various. The light emitting areas PXA having various sizes areillustrated as an example in FIG. 9; however, exemplary embodiments arenot limited thereto or thereby. In some exemplary embodiments, the sizesof the light emitting areas PXA may be equal to each other, and thesizes of the touch openings TS-OP may also be equal to each other.

FIGS. 9 and 10A illustrate a touch sensor SP exposed to the outside.Alternatively, the display module DM may further include an insulatinglayer that is disposed on the thin film sealing layer TFE to cover thefirst touch sensor SP.

Referring to FIG. 10B, a touch sensor SP-MR may include a first touchelectrode MLT1, an insulating pattern CNT, and a second touch electrodeMLT2. The insulating pattern CNT insulates the first touch electrodeMLT1 from the second touch electrode MLT2. Each of the first and secondtouch electrodes MLT1 and MLT2 may reflect incident light. Thus, thefirst and second touch electrodes MLT1 and MLT2 may provide a mirrorfunction to a user.

FIG. 11A is a plan view illustrating touch sensors SP disposed in atouch sensing area TA according to some exemplary embodiments. FIG. 11Bis a cross-sectional view taken along sectional line I-I′ of FIG. 2Aaccording to some exemplary embodiments.

Referring to FIG. 11A, a touch sensing unit TS includes touch sensors SPand connection patterns CP, which are disposed in the touch sensing areaTA.

The touch sensors SP may include first touch sensors SP1 and secondtouch sensors SP2. The first touch sensors SP1 may be arranged toconstitute a plurality of columns parallel to the first direction DR1,and each of the columns may include the first touch sensors SP1 that arearranged in the first direction DR1 and are electrically connected toeach other. The columns of the first touch sensors SP1 may be arrangedin the second direction DR2. Each of the first touch sensors SP1 mayhave a mesh shape in which a plurality of touch openings TS-OP isdefined.

The second touch sensors SP2 may be insulated from the first touchsensors SP1 by insulating patterns CNT. The insulating patterns CNT mayinclude at least one of an inorganic material and an organic material.The inorganic material may include at least one of silicon oxide andsilicon nitride. The organic material may include at least one of anacrylic-based resin, a methacrylic-based resin, polyisoprene, avinyl-based resin, an epoxy-based resin, a urethane-based resin, acellulose-based resin, and a perylene-based resin.

The second touch sensors SP2 may be arranged to constitute a pluralityof rows parallel to the second direction DR2, and each of the rows mayinclude the second touch sensors SP2 that are arranged in the seconddirection DR2 and are electrically connected to each other. Each of thesecond touch sensors SP2 may have a mesh shape in which a plurality oftouch openings TS-OP is defined.

The connection patterns CP may include first connection patterns CP1 andsecond connection patterns CP2. Each of the first connection patternsCP1 connects adjacent first touch sensors SP1. Each of the secondconnection patterns CP2 connects adjacent second touch sensors SP2.

In some exemplary embodiments, at least one of the first touch sensorsSP1 and the second touch sensors SP2 may include a conductive polymermaterial. The conductive polymer material may include apolythiophene-based compound, a polypyrrole-based compound, apolyaniline-based compound, a polyacetylene-based compound, apolyphenylene-based compound, or any mixture thereof. For instance, theconductive polymer material may include PEDOT/PSS among thepolythiophene-based compounds. The conductive polymer material may beeasily manufactured. In addition, flexibility of the conductive polymermaterial may be higher than that of a conductive metal oxide (e.g.,ITO), and, thus, the possibility of occurrence of a crack in theconductive polymer material may be reduced when the conductive polymermaterial is bent.

In some exemplary embodiments, the first connection patterns CP1 or thesecond connection patterns CP2 may have a bridge function.

The first touch sensors SP1 may be capacitively coupled to the secondtouch sensors SP2. In some exemplary embodiments, the first touchsensors SP1 may transmit electric fields, and the second touch sensorsSP2 may receive the electric fields transmitted from the first touchsensors SP1. In other exemplary embodiments, the second touch sensorsSP2 may transmit electric fields, and the first touch sensors SP1 mayreceive the electric fields transmitted from the second touch sensorsSP2.

The above mentioned shapes of the first and second touch sensors SP1 andSP2 are provided as an example. However, exemplary embodiments are notlimited thereto or thereby. In some exemplary embodiments, each of thefirst and second touch sensors SP1 and SP2 may have a bar shape having auniform width.

The first touch sensors SP1 and the second touch sensors SP2 may bedisposed symmetrically with respect to the bending axis BX.

Referring to FIG. 11B, the first touch sensor SP1 overlaps with thesecond touch sensor SP2 in the in-folding mode in which the displaydevice DD is in-folded along the bending axis BX. In this manner, thefirst touch sensor SP1 and the second touch sensor SP2 overlapping witheach other are capacitively coupled to each other. When externalpressure is applied, a capacitance between the first and second touchsensors SP1 and SP2 capacitively coupled to each other may be changedand the display device DD may sense the change in the capacitance tomeasure the external pressure.

As described above, the display device DD may sense a touch of a user inthe normal mode and may sense pressure applied by a user in thein-folding mode. However, exemplary embodiments are not limited theretoor thereby. In some exemplary embodiments, the touch sensing unit TS maynot sense the applied pressure.

FIG. 12A is a plan view illustrating touch sensors SP-1 disposed in atouch sensing area TA according to some exemplary embodiments. FIG. 12Bis a cross-sectional view taken along sectional line I-I′ of FIG. 2Aaccording to some exemplary embodiments.

Referring to FIG. 12A, a touch sensing unit TS-1 includes touch sensorsSP-1 and connection patterns CP that are disposed in the touch sensingarea TA. Te touch sensors SP-1 may include first touch sensors SP1-1 andsecond touch sensors SP2-1. Unlike the touch sensors SP illustrated inFIGS. 11A and 11B, the same kind of the touch sensors SP-1 aresymmetrical with respect to the bending axis BX in FIG. 12A. Forexample, one or some of the first touch sensors SP1-1 and another orothers of the first touch sensors SP1-1 are disposed symmetrically withrespect to the bending axis BX. In addition, one or some of the secondtouch sensors SP2-1 and another or others of the second touch sensorsSP2-1 are disposed symmetrically with respect to the bending axis BX.

Referring to FIG. 12B, the one or some of the first touch sensors SP1-1may overlap with the another or others of the first touch sensor SP1-1in the in-folding mode in which the display device DD is in-folded alongthe bending axis BX. At this time, the first touch sensors SP1-1, whichoverlap with each other, are capacitively coupled to each other. Whenexternal pressure is applied, a capacitance between the first touchsensors SP1-1 capacitively coupled to each other may be changed and thedisplay device DD may sense the change in the capacitance to measure theexternal pressure.

In the normal mode, the first touch sensors SP1-1 of a display deviceDD-1 may selectively perform one of a function of transmitting electricfields and a function of receiving the electric fields. However, in thein-folding mode of the display device DD-1, one of the overlapping twofirst touch sensors SP1-1 transmits the electric field and the other ofthe overlapping two first touch sensors SP1-1 receives the electricfield.

In the normal mode, the second touch sensors SP2-1 of the display deviceDD-1 may selectively perform one of a function of transmitting electricfields and a function of receiving the electric fields. However, in thein-folding mode of the display device DD-1, one of overlapping twosecond touch sensors SP2-1 transmits the electric field and the other ofthe overlapping two second touch sensors SP2-1 receives the electricfield.

The integrated circuit DIC (see FIG. 8) may control the role change ofthe first and second touch sensors SP1-1 and SP2-1 according to the modechange between the normal mode and the in-folding mode.

FIG. 13 is a block diagram illustrating a display device according tosome exemplary embodiments.

Referring to FIG. 13, the display device DD may further include a sensorcontroller SC and a display driving part PCA.

The sensor controller SC may control operations of the fingerprintrecognition unit FPS and may sense, for example, the change in amount oflight in the fingerprint recognition unit FPS to recognize a fingerprintof a user.

The display driving part PCA may supply an image driving signal to thedisplay panel DP to control an image displaying operation of the displaypanel DP. To achieve this, the display driving part PCA may generate theimage driving signal using image data and a control signal that aresupplied from the outside. For example, the display driving part PCA maybe supplied with the image data and the control signal from a host (notshown), and the control signal may include a vertical synchronizationsignal, a horizontal synchronization signal, and/or a main clock signal.In addition, the image driving signal may include a scan signal and datasignals generated using the image data.

In some exemplary embodiments, the sensor controller SC may beintegrated with the display driving part PCA. For example, the sensorcontroller SC and the display driving part PCA may be realized as asingle integrated circuit (IC).

FIG. 14A is a perspective view illustrating a display device DD1 in anormal mode according to some exemplary embodiments. FIGS. 14B and 14Care perspective views illustrating the display device DD1 of FIG. 14A inout-folding modes according to various exemplary embodiments. Thedisplay device DD1 in a normal mode in FIG. 14A may be substantially thesame as the display device DD in the normal mode in FIG. 1, and, thus,duplicative descriptions will be omitted.

As illustrated in FIG. 14B, the display device DD1 may be outer-bentsuch that a display surface IS of the display device DD1 is exposed tothe outside. For the purposes of this specification, a case in which aback surface of a first non-bending area NBA1 faces a back surface of asecond non-bending area NBA2 is defined as the out-folding mode. A casewhich is not the out-folding mode may be defined as the normal mode.

FIG. 14C illustrates another example of the display device DD1, andillustrates the display device DD1 of which a folding portion isdifferent from that of the display device DD1 of FIG. 14B. As such,exemplary embodiments are not limited to or by the numbers of thebending area BA and the non-bending area NBA of the display device DD1or a position of the bending area of the display device DD1.

A user can set security and/or control the display device DD1 throughfingerprint recognition even though the display device DD1 is in theout-folding mode, and, thus, convenience of a user can be improved.

FIG. 15A is a cross-sectional view taken along a line III-III′ of FIG.14A to illustrate a display device according to some embodiments of theinvention. FIG. 15B is a cross-sectional view taken along a line IV-IV′of FIG. 14B to illustrate a display device according to some embodimentsof the invention.

Referring to FIG. 15A, a force sensor FSS is disposed under the displaymodule DM. The force sensor FSS includes a first force-sensing electrodeFS1 and a second force-sensing electrode FS2. The first force-sensingelectrode FS1 and the second force-sensing electrode FS2 may besymmetrical with respect to the bending axis BX.

Referring to FIG. 15B, the first force-sensing electrode FS1 overlapswith the second force-sensing electrode FS2 in the out-folding mode. Thefirst and second force-sensing electrodes FS1 and FS2 overlapping witheach other are capacitively coupled to each other. When externalpressure is applied, a capacitance between the first and secondforce-sensing electrodes FS1 and FS2 capacitively coupled to each othermay be changed and the display device DD1 may sense the change in thecapacitance to measure the external pressure.

FIG. 16A is a cross-sectional view taken along sectional line III-III′of FIG. 14A according to some exemplary embodiments. FIG. 16B is across-sectional view taken along sectional line IV-IV′ of FIG. 14Baccording to some exemplary embodiments. FIG. 16C illustrates straingauges SG1 and SG2 of FIG. 16A according to some exemplary embodiments.

Referring to FIG. 16A, a force sensor FSS-1 is disposed under thedisplay module DM. The force sensor FSS-1 includes strain gauges SG1 andSG2. The strain gauges SG1 and SG2 may include a first strain gauge SG1and a second strain gauge SG2. The first strain gauge SG1 may bedisposed to overlap with the first non-bending area NBA1, and the secondstrain gauge SG2 may be disposed to overlap with the second non-bendingarea NBA2. The strain gauge SG1 and SG2 is used to measure pressure,torque, or stress using a pressure resistance effect that a resistancevalue of a resistor formed of a metal or semiconductor is varied whenthe resistor is deformed.

Referring to FIG. 16C, a metal pattern of each of the strain gauges SG1and SG2 may have a specific direction. The direction of the metalpattern of one of the strain gauges SG1 and SG2 may be perpendicular tothe direction of the metal pattern of another, adjacent to the onestrain gauge, of the strain gauges SG1 and SG2. Like this, the straingauges SG1 and SG2 may be disposed such that the directions of the metalpatterns are perpendicular to each other, and thus, the sensitivity ofmeasuring pressure may be improved.

FIG. 17 is a perspective view illustrating a display device DD2according to some exemplary embodiments. The display device DD2 of FIG.17 is similar to the display device DD of FIG. 1, and, therefore,duplicative descriptions are omitted.

The display device DD2 is a both surface light-emitting display devicethat provides images IM1 and IM2 through its front surface and backsurface. The display device DD2 provides a first image IM1 through thefront surface. In FIG. 17, application icons are illustrated as anexample of the first image IM1. The display device DD2 provides a secondimage IM2 through the back surface. In FIG. 17, a bear doll image isillustrated as an example of the second image IM2. A fingerprintrecognition area FPA-1 may be defined in at least one of the frontsurface and the back surface of the display device DD2. The fingerprintrecognition area FPA-1 may be substantially the same as the fingerprintrecognition area FPA of FIG. 1. A fingerprint recognition unit may beincluded in the display device DD2 and may overlap with the fingerprintrecognition area FPA-1. The fingerprint recognition unit of the displaydevice DD2 may be one of the fingerprint recognition units FPS and FPS-Edescribed with reference to FIGS. 3A to 3D.

FIG. 18 is a partial cross-sectional view illustrating the displaydevice DD2 according to some exemplary embodiments.

As seen in FIG. 18, the display device DD2 includes a display panelDP-1, a touch sensing unit TS, a first force sensor FSS1, and a secondforce sensor FSS2. The display panel DP-1 includes a transparent baselayer SUB-TP, an insulating layer 16-1, and a light-emitting elementlayer ELL-1.

The transparent base layer SUB-TP may transmit at least a portion ofincident light. For example, the transparent base layer SUB-TP mayinclude glass. The insulating layer 16-1 is disposed on the transparentbase layer SUB-TP. A function and a material of the insulating layer16-1 may be substantially the same as those of the third insulatinglayer 16 of FIGS. 6 and 7, and, thus, duplicative descriptions will beomitted. The light-emitting element layer ELL-1 is disposed on theinsulating layer 16-1. The light-emitting element layer ELL-1 includes alight-emitting element OLED-1. The light-emitting element OLED-1 mayinclude a front surface light emitting area LA-F and a back surfacelight emitting area LA-B.

The light-emitting element OLED-1 includes a first reflection layer RF1,a first anode AE1, a second anode AE2, a light-emitting layer EML, acathode CE, and a second reflection layer RF2.

The first reflection layer RF1 is disposed on the insulating layer 16-1and overlaps with the front surface light emitting area LA-F. The firstreflection layer RF1 may reflect incident light, e.g., reflect incidentlight toward touch sensing unit TS.

The first anode AE1 is disposed on the first reflection layer RF1 andoverlaps with the front surface light emitting area LA-F. The secondanode AE2 is disposed on the insulating layer 16-1 and overlaps with theback surface light emitting area LA-B.

The light-emitting layer EML is disposed on the first anode AE1 and thesecond anode AE2, and overlaps with the front surface light emittingarea LA-F and the back surface light emitting area LA-B. The cathode CEis disposed on the light-emitting layer EML, and overlaps with the frontsurface light emitting area LA-F and the back surface light emittingarea LA-B. The second reflection layer RF2 is disposed on the cathodeCE, and overlaps with the back surface light emitting area LA-B. Thesecond reflection layer RF2 may reflect incident light, e.g., reflectincident light towards transparent base layer SUB-TP.

Light generated in the light-emitting layer EML is reflected by thefirst reflection layer RF1 so as to be emitted to the front surface ofthe display device DD2. Light generated in the light-emitting layer EMLis reflected by the second reflection layer RF2 so as to be emitted tothe back surface of the display device DD2. Thus, the light-emittingelement OLED-1 may emit the light to the front surface and the backsurface of the display device DD2.

The first force sensor FSS1 is disposed on the second reflection layerRF2, and overlaps with the back surface light emitting area LA-B. Thefirst force sensor FSS1 may sense pressure applied to the display deviceDD2. The first force sensor FSS1 may include a strain gauge. The touchsensing unit TS may be disposed on the first force sensor FSS1.

The second force sensor FSS2 is disposed under the display panel DP-1.When the display device DD2 is folded, the second force sensor FSS2 maysense pressure applied to the display device DD2. The second forcesensor FSS2 includes a first force-sensing electrode FS1 and a secondforce-sensing electrode FS2. The first and second force-sensingelectrodes FS1 and FS2 may be substantially the same as described withreference to FIG. 15A, and, thus, duplicative descriptions will beomitted.

FIG. 19 is a partial cross-sectional view illustrating a display deviceDD2-1 according to some embodiments of the invention.

The display device DD2-1 includes a display panel DP-2, a touch sensingunit TS, a first force sensor FSS1-1, a second force sensor FSS2, and areflection member MR. The display panel DP-2 includes a transparent baselayer SUB-TP, an insulating layer 16-1, a light-emitting element layerELL-1, and a planarization layer FLL1.

The reflection member MR is disposed on the planarization layer FLL1.The reflection member MR is disposed between the first force sensorsFSS1-1. The reflection member MR may reflect light to provide a mirrorfunction to a user.

The planarization layer FFL1 covers the light-emitting element layerELL-1 and provides a planarized surface. The planarization layer FLL1may include an organic material. In some exemplary embodiments, theplanarization layer FLL1 may act as a sealing material that seals thelight-emitting element layer ELL-1.

The first force sensor FSS1-1 is similar to the first force sensor FSS1of FIG. 18, however, the first force sensor FSS1-1 may be disposed onthe planarization layer FLL1. The first force sensor FSS1-1 may becovered with an additional planarization layer FFL2.

Other components of the display device DD2-1 may be substantially thesame as described with reference to FIG. 18, and, thus, duplicativedescriptions will be omitted.

FIG. 20 is a partial cross-sectional view illustrating a display deviceDD2-2 according to some exemplary embodiments.

The display device DD2-2 includes a display panel DP-1, a reflectionmember MR, a first force sensor FSS1, and a second force sensor FSS2.

The reflection member MR is disposed on the first force sensor FSS1 andoverlaps with the front surface light emitting area LA-F and the backsurface light emitting area LA-B. The reflection member MR may reflectlight to provide a mirror function to a user. The reflection member MRmay be capacitively coupled to the first force sensor FSS1 to sense atouch of a user. For example, the reflection member MR and the firstforce sensor FSS1 may sense a touch by a self-capacitance method.

FIG. 21 is a cross-sectional view illustrating a display device DD2-3according to some exemplary embodiments.

The display device DD2-3 includes a first display module DM1, a seconddisplay module DM2, and a force sensor FSS3. Each of the first andsecond display modules DM1 and DM2 may be substantially the same as thedisplay module DM described with reference to FIGS. 3 to 7, and, thus,duplicative descriptions will be omitted. The force sensor FSS3 isdisposed between the first display module DM1 and the second displaymodule DM2. The force sensor FSS3 may sense pressure applied to thedisplay device DD2-3.

FIGS. 22, 23, 24, 25, and 26 are cross-sectional views illustratingforce sensors FSS3, FSS3-1, FSS3-2, FSS3-3, and FSS3-4 according tovarious exemplary embodiments.

Referring to FIG. 22, the force sensor FSS3 includes an insulating layerLPI, a buffer layer BF-FSS, a pressure cushion PC, a first force-sensingelectrode FS1, and a second force-sensing electrode FS2. In someexemplary embodiments, the force sensor FSS3 may include the insulatinglayer LPI, the second force-sensing electrode FS2, the buffer layerBF-FSS, the insulating layer LPI, the pressure cushion PC, theinsulating layer LPI, the buffer layer BF-FSS, the first force-sensingelectrode FS1 and the insulating layer LPI which are stacked in theorder listed. However, exemplary embodiments are not limited to or bythe stack order of the force sensor FSS3. In some exemplary embodiments,the insulating layer LPI, the buffer layer BF-FSS, the pressure cushionPC, the first force-sensing electrode FS1, and the second force-sensingelectrode FS2 may be stacked in another stack order.

The first force-sensing electrode FS1 is capacitively coupled to thesecond force-sensing electrode FS2. In some exemplary embodiments, thefirst force-sensing electrode FS1 may transmit an electric field and thesecond force-sensing electrode FS2 may receive the electric field. Insome exemplary embodiments, roles of the first and second force-sensingelectrodes FS1 and FS2 of the force sensor FSS3 may be changed with eachother, according to a driving mode. For example, in a first drivingmode, the first force-sensing electrode FS1 may transmit the electricfield and the second force-sensing electrode FS2 may receive theelectric field. In a second driving mode, the second force-sensingelectrode FS2 may transmit the electric field and the firstforce-sensing electrode FS1 may receive the electric field.

Referring to FIG. 23, the first force-sensing electrode FS1 of the forcesensor FSS3-1 may be electrically connected to the touch sensing unit TSof the first display module DM1 through a sixth through-hole CH6 in theinsulating layer LPI-1. The second force-sensing electrode FS2 of theforce sensor FSS3-1 may be electrically connected to the touch sensingunit TS of the second display module DM2 through a seventh through-holeCH7 in the insulating layer LPI-1. In this manner, the force sensorFSS3-1 may be driven and controlled by electrical signals supplied fromthe touch sensing units TS.

Referring to FIG. 24, first and second force-sensing electrodes FS1 andFS2 of the force sensor FSS3-2 may be alternately arranged on the samelayer in a lateral direction, e.g., in the first direction DR1.

Referring to FIG. 25, the force sensor FSS3-3 may include the insulatinglayer LPI, the buffer layer BF-FSS, the insulating layer LPI, the secondforce-sensing electrode FS2, the pressure cushion PC, the firstforce-sensing electrode FS1, the insulating layer LPI, the buffer layerBF-FSS, and the insulating layer LPI that are stacked in the orderlisted.

Referring to FIG. 26, the force sensor FSS3-4 may further include anoise-shielding layer NSL. The noise-shielding layer NSL may be disposedbetween the insulating layer LPI and the buffer layer BF-FSS. However,exemplary embodiments are not limited to or by the position of thenoise-shielding layer NSL. The noise-shielding layer NSL may shieldnoise occurring from transistors of the first and second display modulesDM1 and DM2, and, thus, the force sensor FSS3-4 may more effectivelysense pressure.

FIGS. 27, 28, and 29 illustrate touch sensing units TS2, TS3, and TS4according to various exemplary embodiments.

Referring to FIG. 27, a touch sensor SP-TS2 of the touch sensing unitTS2 may have a stripe pattern shape, unlike the touch sensor SP of thetouch sensing unit TS.

Referring to FIGS. 28 and 29, each of touch sensors SP-TS3 and SP-TS4 ofthe touch sensing units TS3 and TS4 may have a shape including aplurality of quadrilateral patterns, unlike the touch sensor SP of thetouch sensing unit TS.

FIG. 30A is a perspective view illustrating a display device DD3 in anormal mode according to some exemplary embodiments. FIG. 30B is aperspective view illustrating the display device DD3 of FIG. 30A in anin-folding mode according to some exemplary embodiments. The displaydevice DD3 is similar to the display devices DD, DD1, and DD2, and,therefore, duplicative descriptions will be primarily omitted.

Referring to FIG. 30A, the display device DD3 may include a firstdisplay area DD-DA1, a second display area DD-DA2, and a non-displayarea DD-NDA. In some exemplary embodiments, the first display areaDD-DA1 and the second display area DD-DA2 may display images IMindependently of each other. In some exemplary embodiments, the firstdisplay area DD-DA1 and the second display area DD-DA2 may displayimages IM which are dependent on each other.

Referring to FIG. 30B, a portion of the display device DD3, whichcorresponds to the first display area DD-DA1, may be bent or folded.Likewise, another portion of the display device DD3, which correspondsto the second display area DD-DA2, may be bent or folded. In anin-folding mode, the fingerprint recognition area FPA of the displaydevice DD3 may be exposed to the outside. The display device DD3 in thein-folding mode is illustrated in FIG. 30B. However, exemplaryembodiments are not limited thereto or thereby. In some exemplaryembodiments, the display device DD3 may be out-folded.

FIG. 31A is a perspective view illustrating a display device DD4 in anormal mode according to some exemplary embodiments. FIGS. 31B and 31Care perspective views illustrating the display device DD4 of FIG. 31A infolding modes according to various exemplary embodiments.

The display device DD4 may include a first bending area BA1, a secondbending area BA2, a first non-bending area NBA1, a second non-bendingarea NBA2, and a third non-bending area NBA3 on the basis of bendingaxes BX. The display device DD4 may be in-folded such that a portion ofthe display surface IS of the first non-bending area NBA1 faces aportion of the display surface IS of the second non-bending area NBA2,and may be out-folded such that a portion of the display surface IS ofthe second non-bending area NBA2 does not face a portion of the displaysurface IS of the third non-bending area NBA3.

Referring to FIG. 31B, in some exemplary embodiments, a fingerprintrecognition area FPA may be formed in (or on) a back surface of thedisplay device DD4. In other words, the fingerprint recognition area FPAmay be formed on a surface opposite to the display surface IS of thedisplay device DD4.

Referring to FIG. 31C, in some exemplary embodiments, the fingerprintrecognition area FPA may be formed in (or on) a front surface of thedisplay device DD4. In other words, the fingerprint recognition area FPAmay be formed on the display surface IS of the display device DD4.

As illustrated in FIGS. 31A to 31C, the fingerprint recognition area FPAis exposed to the outside even though the display device DD4 is folded.Thus, a user may touch the exposed fingerprint recognition area FPA andmay conveniently use the display device DD4.

FIG. 32A is a cross-sectional view taken along sectional line V-V′ ofFIG. 31B according to some exemplary embodiments. FIG. 32B is across-sectional view taken along sectional line VI-VI′ of FIG. 31Caccording to some exemplary embodiments.

The display device DD4 may sense pressure applied from the outside usingthe force sensor FSS and the touch sensors SP1 and SP2. The force sensorFSS includes a first force-sensing electrode FS1 and a secondforce-sensing electrode FS2. The force sensor FSS and the touch sensorsSP1 and SP2 may be substantially the same as described above, and, thus,duplicative descriptions will be omitted. In some exemplary embodiments,however, the display device DD4 may include the force sensor FSS-1described with reference to FIG. 16A. The force sensor FSS-1 may includethe strain gauges SG1 and SG2 of FIG. 16C. The force sensor FSS-1 may besubstantially the same as described above, and, thus, duplicativedescriptions will be omitted.

FIG. 33 is a perspective view illustrating a display device DD5according to some exemplary embodiments.

In one or more exemplary embodiments, the display device DD5 is awatch-type wearable device that can be worn on a wrist. The displaydevice DD5 includes a display area DD-DA and a fingerprint recognitionarea FPA. In some exemplary embodiments, the display area DD-DA mayinclude the fingerprint recognition area FPA. In other exemplaryembodiments, the display area DD-DA and the fingerprint recognition areaFPA may be separated from each other.

The fingerprint recognition area FPA may sense a touch of a user and/ormay recognize a fingerprint of a user. The fingerprint recognition areaFPA may be realized using an active self-capacitance (ASC) method, amutual capacitance method, a self-capacitance method, an ultrasonicmethod, or an optical sensing method. However, the method of realizingthe fingerprint recognition area FPA is not limited thereto or thereby.In some exemplary embodiments, the fingerprint recognition area FPA mayuse at least one of other various methods capable of sensing a touchand/or a fingerprint.

Signal lines and insulating layers of the fingerprint recognition areaFPA and the display area DD-DA may be formed on the same layer.

The fingerprint recognition area FPA recognizes a fingerprint and sensesa touch signal, and, thus, operations of a display panel of the displaydevice DD5 can be performed. In other words, when the fingerprintrecognition area FPA is formed by the active self-capacitance (ASC)method, gate lines and data lines of the fingerprint recognition areaFPA may be formed on the same layer as gate lines GL (see FIG. 4) anddata lines DL (see FIG. 4) of the display area DD-DA. In addition,transistors of the ASC method may be formed by the same processes astransistors TFT1 and TFT2 (see FIG. 5) of the display area DD-DA.

In other exemplary embodiments, when a fingerprint recognition unit or atouch sensing unit is formed by the mutual capacitance method or theself-capacitance method, touch sensor interconnections of the touchsensing unit and touch interconnections of the display area DD-DA may beformed at the same time.

FIGS. 34A and 34B are plan views illustrating touch sensing units TS5and TS6 according to various exemplary embodiments.

The touch sensing units TS5 and TS6 may include different kinds of touchsensors SP-1 and SP-TS4 or SP-TS5 disposed at both sides of a bendingaxis BX, respectively. For example, one of the touch sensors SP-1 andSP-TS4 or SP-TS5 may be a mutual capacitance type touch sensor (e.g.,touch sensor SP-1), and the other of the touch sensors SP-1 and SP-TS4or SP-TS5 may be a self-capacitance type touch sensor (e.g., touchsensor SP-TS4 or SP-TS5).

The touch sensing units TS5 and TS6 have different characteristics onthe basis of the structures of the touch sensors SP-1 and SP-TS4 orSP-TS5. For example, the mutual capacitance type structure can reducethe number of channels, and the self-capacitance type structure may haveadvantages of a hovering touch. Thus, as occasion demands, the touchsensing units TS5 and TS6 may have the advantages of the mutualcapacitance method and the advantages of the self-capacitance method bychanging the kinds of the touch sensors SP-1 and SP-TS4 or SP-TS5included in the touch sensing unit TS5 and TS6.

In other exemplary embodiments, a portion of the touch sensing units TS5and TS6 may be used to recognize a fingerprint. In this case, a portionof the touch sensors may have a size (e.g., a diameter or width) ofabout 50 micrometers to about 200 micrometers.

FIG. 35 is a cross-sectional view illustrating a display device DD6 inan in-folding state according to some exemplary embodiments. FIG. 36 isa cross-sectional view illustrating the display device DD6 in anout-folding state according to some exemplary embodiments.

Referring to FIG. 35, the display device DD6 including the touch sensingunit TS5 or TS6 of FIG. 34A or 34B may be in-folded. Referring to FIG.36, the display device DD6 including the touch sensing unit TS5 or TS6of FIG. 34A or 34B may be out-folded.

FIG. 37 is a cross-sectional view illustrating a display device DD7 inan out-folding state according to some exemplary embodiments. Thedisplay device DD7 including the touch sensing unit TS5 or TS6 of FIG.34A or 34B may include a force sensor FSS-2 that is disposed on abending portion of the display device DD7. The force sensor FSS-2 maysense or detect whether the display device DD7 is bent or not. The forcesensor FSS-2 may include the strain gauges SG1 and S G2 of FIG. 16C.

According to various exemplary embodiments, in an in-folding mode, adisplay device may sense applied pressure through a capacitance-typetouch sensing unit for sensing a touch of a user. A display device,according to some exemplary embodiments, may sense applied pressurethrough a force sensor in an out-folding mode. In various exemplaryembodiments, a display device may be a both surface display deviceproviding images in both directions and may sense applied pressurethrough a force sensor.

Although certain exemplary embodiments and implementations have beendescribed herein, other embodiments and modifications will be apparentfrom this description. Accordingly, the inventive concepts are notlimited to such embodiments, but rather to the broader scope of thepresented claims and various obvious modifications and equivalent isarrangements.

What is claimed is:
 1. A display device comprising: a flexible displaymodule, wherein the display device provides: a display area comprising afingerprint recognition area; and a non-display area outside the displayarea, wherein the flexible display module comprises: a display panelcomprising a light-emitting element; a touch sensing unit disposed onthe display panel; and a fingerprint recognition unit overlapping thefingerprint recognition area, and wherein the touch sensing unit isconfigured to sense pressure applied to the flexible display module inan in-folding mode in which the flexible display module is folded suchthat a portion of the display area faces another portion of the displayarea.
 2. The display device of claim 1, wherein the display panel isdisposed between the touch sensing unit and the fingerprint recognitionunit.
 3. The display device of claim 2, wherein the fingerprintrecognition unit comprises at least one of an optical sensing module andan ultrasonic sensing module.
 4. The display device of claim 3, whereineach of the optical sensing module and the ultrasonic sensing modulecomprises: a signal generator configured to transmit a first signaltowards a fingerprint of a user; and a signal receiver configured toreceive a second signal corresponding to a reflection of the firstsignal from the fingerprint of the user.
 5. The display device of claim1, wherein the touch sensing unit is disposed between the fingerprintrecognition unit and the display panel.
 6. The display device of claim5, wherein the fingerprint recognition unit comprises a capacitance-typesensing module.
 7. The display device of claim 1, wherein thefingerprint recognition area is exposed to an outside in the in-foldingmode.
 8. The display device of claim 1, wherein: the touch sensing unitcomprises: first touch sensors configured to transmit electric fields;and second touch sensors configured to receive the electric fields; andat least one of the first touch sensors overlaps with at least one ofthe second touch sensors in the in-folding mode.
 9. The display deviceof claim 8, wherein at least one of the first touch sensors and thesecond touch sensors comprises a conductive polymer material.
 10. Thedisplay device of claim 9, wherein the conductive polymer materialcomprises at least one of a polythiophene-based compound, apolypyrrole-based compound, a polyaniline-based compound, apolyacetylene-based compound, and a polyphenylene-based compound. 11.The display device of claim 8, wherein sensation of the pressurecomprises sensation of a change in capacitance between the at least oneof the first touch sensors and the at least one of the second touchsensors in the in-folding mode.
 12. The display device of claim 1,wherein: the touch sensing unit comprises: first touch sensors; andsecond touch sensors capacitively coupled to the first touch sensors;and at least one of the first touch sensors overlaps with at leastanother one of the first touch sensors in the in-folding mode.
 13. Thedisplay device of claim 12, wherein sensation of the pressure comprisessensation of a change in capacitance between the at least one of thefirst touch sensors and the at least another one of the first touchsensors in the in-folding mode.
 14. The display device of claim 1,wherein: the light-emitting element comprises a front surface lightemitting area and a back surface light emitting area; and the displaypanel is a both surface light-emitting display panel.
 15. A displaydevice comprising: a flexible display module; and a force sensor,wherein the display device provides: a display area comprising afingerprint recognition area; and a non-display area outside the displayarea, wherein the flexible display module comprises: a display panelcomprising a light-emitting element; a touch sensing unit disposed onthe display panel; and a fingerprint recognition unit overlapping withthe fingerprint recognition area, wherein the display panel is disposedbetween the touch sensing unit and the force sensor, and wherein theforce sensor is configured to sense pressure applied to the flexibledisplay module in an out-folding mode in which the flexible displaymodule is folded such that a portion of the display area faces anopposite direction from another portion of the display area.
 16. Thedisplay device of claim 15, wherein the display panel is disposedbetween the touch sensing unit and the fingerprint recognition unit. 17.The display device of claim 16, wherein the fingerprint recognition unitcomprises at least one of an optical sensing module and an ultrasonicsensing module.
 18. The display device of claim 15, wherein: thefingerprint recognition unit comprises a capacitance-type sensingmodule; and the touch sensing unit is disposed between the fingerprintrecognition unit and the display panel.
 19. The display device of claim15, wherein the force sensor is configured to sense a change incapacitance in the out-folding mode to sense the pressure.
 20. A displaydevice comprising: a flexible display module, wherein the display deviceprovides: a display area comprising a fingerprint recognition area; anda non-display area outside the display area, wherein the flexibledisplay module comprises: a display panel comprising a light-emittingelement; a touch sensing unit disposed on the display panel; and afingerprint recognition unit overlapping with the fingerprintrecognition area, and wherein the touch sensing unit is configured tosense a capacitance between a portion of the display area and anotherportion of the display area in an in-folding mode in which the flexibledisplay module is folded such that the portion of the display area facesthe another portion of the display area.